The URU submachine gun was designed in Brazil by Olympio Vieira de Mello in 1974-75. The production of the new submachine gun was commenced at the company Mekanika Indústria e Comércio Ltda, Rio de Janeiro, in 1977. Total production of the URU submachine guns for Brazilian military and police between 1977 and 1985 is estimated at about 10 thousands guns.

The Mekanika URU submachine gun is a simple blowback weapon which fires from open bolt. It is capable of semi- and full-automatic fire, and combination safety / fire mode selector lever is located on the left side of the trigger unit. The receiver and barrel jacket are made from steel tube, the trigger housing and magazine well / forward grip are made from steel stampings. Gun is equipped with side-folding metallic buttstock. Sights are fixed, comprising of rear aperture and front post, factory zeroed for 50 meters range.